Stock-Based Compensation - Valuation Assumptions for Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Black-Scholes option-pricing model assumptions
Weighted-average grant date fair value of options granted (in dollars per share)	$ 8.16	$ 9.78
Stock Options
Black-Scholes option-pricing model assumptions
Expected volatility, minimum (percent)	46.70%	41.70%
Expected volatility, maximum (percent)	47.20%	47.30%
Risk-free interest rate, minimum (percent)	1.60%	1.30%
Risk-free interest rate, maximum (percent)	1.60%	2.60%
Dividend yield (percent)	0.00%	0.00%
Stock Options | Minimum
Black-Scholes option-pricing model assumptions
Expected term (in years)	5 years 6 months	5 years
Stock Options | Maximum
Black-Scholes option-pricing model assumptions
Expected term (in years)	7 years	7 years